Magnetic field sensors and magnetometers have a wide variety of applications. Some examples of their applications are non-contact current sensors, medical imaging and keyboard sensors. A particularly important application is as the read head of magnetic storage units.
When a magnetic field is applied perpendicular to the current trajectory in a piece of material, the moving charge carriers are subject to the Lorentz force. In a semiconductor material, depending on the material and the operating conditions, the Lorentz force manifests itself as one of the following phenomena: the Hall effect, carder deflection, magnetoconcentration, and magnetoresistance (see for example Baltes et al, "Integrated Semiconductor Magnetic Field Sensors", Proc. 1EEE, Vol 74 No. 8, August 1986, pp. 1107-1132). Known magnetic field sensors or magnetometers exploit one or more of these phenomena in various ways.
At present most magnetometers and sensors are made from a hybrid technology and comprise many discrete components on a small board. An integrated magnetometer or sensor that integrates the basic magnetic sensor with signal conditioning and processing circuitry on the same die can potentially provide a better signal-to-noise ratio, and thus higher sensitivity, and more intelligence than the hybrid magnetometers. Higher sensitivity and faster processing electronics are considered to be necessary to keep up with the advances in magnetic recording technology, and the success of integrating magnetic sensors will be essential for the continued use of the magnetic medium as a low cost, high-density, reliable data storage system, and also for various other applications. The following is a survey of representative known magnetometers and magnetic field sensors.